JPS60239742A - Recording medium - Google Patents

Abstract

PURPOSE:To obtain a high-density recording medium inducible to cause chemical change in a molecular unit by external factor by forming a monomolecular film or built-up monomolecular film of clathrate complexes composed of polymerizable host molecules each having a hydrophilic part, a hydrophobic part, and a clathrating part and guest molecules each to be clathrated with the host molecules on a carrier to form a recording layer. CONSTITUTION:As the host molecule, any molecule having a hydrophilic part and a hydrophobic part and at least one part capable of forming a clathrate complex with another molecule in proper positions, respectively, can be widely used. As the guest molecule capable of forming a clathrate complex with the host molecule, it is desirable for the host molecule to be able to form a strong hydrogen bond in general. Therefore, when the host molecule has a hydroxyl group as mentioned above at the part to clathrate the guest molecule, the guest molecule has aldehyde, ketone, amino, sulfoxide, etc., and in addition, halogen compds, or pi electron type compds., such as alkene, alkyne, and arene. can be selected for the guest molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to a recording medium that performs recording using chemical changes in a monomolecular film or a cumulative monomolecular layer of an inclusion complex.

(2) Background Art Conventionally, various recording media having recording layers made of organic compounds are known.

For example, optical recording media in which a thin film of an organic compound is used as a recording layer are disclosed in, for example, Japanese Patent Laid-Open Nos. 58-18948 and 1982-125248. All of them relate to laser recording media in which recording layers are made of organic dyes and recording and reproduction are performed using laser beams. In particular, the medium disclosed in JP-A-58-125248 uses a thin film of a cyanine dye represented by the general formula (I) as a recording layer. A cyanine dye solution represented by formula (I) is coated on a plastic substrate to a thickness of 100 OA or less, for example, about 300 Å, using a spin coater or the like to form a thin film. If the molecular distribution orientation within the film is random,
Light scattering occurs within the film with light irradiation, and when viewed microscopically, the degree of chemical reaction that occurs differs each time the film is irradiated. Therefore, as a recording medium, it is desirable that the molecular distribution and orientation within the film be uniform, and the film thickness is required to be as thin as possible in order to achieve high density recording. However, when using the coating method, the film thickness is 300
Grade A is the limit, and it is difficult to solve the problem that the molecular distribution and orientation within the film are random.

A diacetylene compound cumulative film, which has been proposed as a resist material with high photon efficiency and excellent resolution, has been used not only as a resist material but also as a thin film electrical
JP-A-58-42229, JP-A-58-43220, etc. show that it can be applied to optical devices, electro-acoustic devices, piezo-pyroelectric devices, etc.

Recently, Japanese Patent Application Laid-Open No. 111029/1983 discloses an improvement in the method for producing a diacetylene compound cumulative film. The diacetylene compound cumulative film on the substrate produced according to the invention can be polymerized by irradiation with ultraviolet rays to form a diacetylene compound polymer film, or masked and irradiated with ultraviolet rays to partially polymerize and remove the unused material. The overlapping portions are removed to create shapes, which are used as thin film optical devices and integrated circuit elements.

However, all of these are limited to diacetylene compounds, and there is no mention of the possibility of erasing once recorded data when used as a thin film optical device.

On the other hand, in order to solve the above-mentioned drawbacks, a monomolecular film or a monomolecular layer stack of one type of photopolymerizable polymer having a parent group, a hydrophobic group, and at least one unsaturated bond in the molecule was deposited on a substrate. An optical recording medium which can be used repeatedly is disclosed in Japanese Patent Application No. 58-190!132, which is characterized in that a recording layer is formed by forming a recording layer.

Whether it is a cumulative film of these diacetylene compounds, a monomolecular film or a monomolecular layer cumulative film of photopolymerizable olefin monomers, a parent group or a hydrophobic group is introduced into a photoreactive compound and the film is directly deposited on a substrate. Adopts a manufacturing method that allows it to be supported. Therefore, although it is difficult to easily produce various functional membranes,
In addition, there was a fear that photoreactivity would decrease due to the introduction of parent wood groups and hydrophobic groups. Furthermore, we are also concerned with the control of molecular orientation within the film plane, which is important when performing extremely advanced high-density recording.
There was a problem that required extremely complicated operations.

We have solved the drawbacks of such conventional examples by providing 1) a method for producing various functional films relatively easily, and 2) a method that eliminates the loss or loss of various functions possessed by functional molecules even when the film is made thin. 3) A method for forming a film in such a way that the film can be expressed without being degraded; As a result of various studies on methods for orientation with an ordered structure, the present invention was accomplished. Furthermore, by using such a film forming method, it has become possible to easily provide a high-sensitivity, high-resolution recording medium with high quality.

(3) Disclosure of the Invention An object of the present invention is to provide a high-density recording medium in which chemical changes occur in molecular units due to external factors.

Another object of the present invention is to provide a medium that is superior to conventional examples in terms of molecular orientation within the medium plane, which is an important factor when performing high-density recording on a molecular basis. Furthermore,
In manufacturing the above-mentioned recording medium, it is an object of the present invention to provide a medium having various properties through relatively simple operational changes.

The above objects of the present invention are achieved by the present invention as follows.

A polymerizable molecule (host molecule) that has a hydrophilic site, a hydrophobic site, and a site that can be included with other molecules (inclusion site) in its molecule, and another type of molecule (guest molecule) that is included in the host molecule. 1. A recording medium comprising, as a recording layer, a monomolecular film or a cumulative monomolecular layer of an inclusion complex consisting of molecules) formed on a carrier.

The substance constituting the recording layer of the present invention is a molecule that has at least one hydrophilic site, one hydrophobic site, and at least one site that can be included with other molecules (this is called a host molecule). It consists of two types of molecules: a different type of molecule (called a guest molecule) that is included in a host molecule. The recording medium of the present invention is formed by forming a monomolecular film or a monomolecular layer cumulative film of an inclusion complex consisting of such a host molecule and a guest molecule on a carrier. However, among these two types of molecules, it is necessary that the host molecule undergoes a chemical or physical change due to an external cause such as light, heat, electricity, or magnetism. That is, the recording medium according to the present invention performs recording using the above-mentioned chemical change.

As the host molecules used in the present invention, as mentioned above,
A wide range of polymerizable molecules can be used as long as they have a hydrophilic site, a hydrophobic site, and at least one site capable of forming an inclusion complex with other species molecules at appropriate positions within the molecule.

Specifically, compounds represented by the following general formula are suitable.

[Example of diacetylene diol derivative]

HH 1 CH3-(CH2) m-C-G: = C-CmiC-
C-(CHz)n-COOH(K)I OH'0H 30≧Recommended+n≧8. n≧0 The above compound is a known compound per se. Also, regarding the point that the host molecule which is not modified with a long button alkyl group etc. forms crystalline inclusion complexes with various guest molecules, Journal of the Chemical Society of Japan No. 2239-242 (1118
3rd year).

Guest molecules that can form inclusion complexes with host molecules include:
Generally, molecules that can form strong hydrogen bonds with host molecules are desirable. Therefore, as mentioned above, when the host molecule has a hydroxyl group as an inclusion site, examples of the guest molecule include aldehydes, ketones, amines, sulfoxides, and the like. In addition, various halogen compounds or π-electron compounds such as alkenes, alkynes, and arenes can also be selected as guest molecules. In any event, molecules are chosen whose structure the inclusion complex formed exhibits the desired imaging function.

Specific examples of guest molecules that can be used for various functions are shown below.

(1) Specific examples of guest molecules that can be used in optical recording media using duplication reactions of guest molecules include olefin compounds (No. 31 to No. 34), diolefin compounds (
1'&), 35-No, 38), anthracene derivatives (
Ilb, 313), 2-7 minopyridinium (No,
41), etc., 81 R--H, -〇, horse, -OH, -0CI (,) 8B floor 88 NC-CI-CH-CN 184 R,OOC-CM-CM-COOR, (RI-R ,-C
MIl or He-CM, , R, --H) [Example of diolefin compound] Floor 85 Ar'-CH-CH-Ar-CH-CH-Ar'n
86 Positive 87 [Example of anthracene derivative] 隘89 (R--CH,,-CHO, -COOC,H,,-
Br) [Example of aclidinicum derivative] n40 R + (R--He-C)I3. -C,H,,X--I,
Br, CI3 [2-aminoviridinicum] Floor 41 (2) Specific examples of guest molecules that can be used in recording media that utilize sublimation of guest molecules include ketones (Level 48),
IJ-epoxy (epoxy such as propane)' (1m4B
), ethyleneimine (Nn44), benzene (Nn45
), dichloromethane, chloroform, and other chlorides (1 m
46, Nn4? ), bromides (+1
kL48) etc., 1 tk 4S R-C-R (R--CH,, -C,H,)
positive, 46 082C1Z positive, 47 CMCl3 No, and 48 CH3Br.

For example, the Langmuir-Prodgett method (LB method) developed by El Angmuir et al. is used as a method for creating a monomolecular film or a monomolecular stacked film of an inclusion complex consisting of a host molecule and a guest molecule. The LB method is
For example, in a molecule with a structure that has a parent wood group and a hydrophobic group in the molecule, when the balance between the two (amphiphilic balance) is maintained appropriately, the molecule will stand alone on the water surface with the parent wood group facing down. This method utilizes the layering of molecules to create a monomolecular film or a cumulative film of monomolecular layers. A monolayer on the water surface has the characteristics of a two-dimensional system. When the molecules are sparsely dispersed, the equation for a two-dimensional ideal gas exists between the area per molecule A and the surface pressure ■.

nA = kT holds true, resulting in a "gas film'°. Here, k is Portzmann's constant and T is the absolute temperature. If A is made sufficiently small, the intermolecular interaction becomes strong and a two-dimensional solid "condensed film (or The condensed film can be transferred layer by layer to the surface of a carrier having various materials and shapes, such as a glass substrate. Using this method, the host molecules that include the guest molecules of the present invention can be transferred layer by layer. Specific methods for producing a monolayer film (hereinafter referred to as a single complex molecular film) or a single complex molecular layer stacked film include, for example, the following five methods A to H [A] The host molecule and guest molecule of the desired inclusion complex are dissolved in a solvent, and this is spread on an aqueous phase to precipitate the inclusion complex in the form of a film.When the structure of the host molecule is as shown in formula l, If the molecule has both a hydrophilic site (carboxyl group) and a hydrophobic site (alkyl group) at both ends, the inclusion complex that precipitates on the aqueous phase will be formed regardless of the hydrophilicity and hydrophobicity of the guest molecule. , the host molecule is spread on the aqueous phase with its hydrophilic site facing toward the aqueous phase.

Next, to prevent this precipitate from freely diffusing on the aqueous phase and spreading too much, a partition plate (or float) is installed to limit the area of development and control the state of aggregation of the membrane material, and Obtain the surface pressure n. By moving this partition plate, the developed area can be reduced to control the aggregation state of the film material, and the surface pressure can be gradually increased to set a surface pressure n suitable for producing a cumulative film. By gently raising and lowering the clean carrier vertically while maintaining this surface pressure, the monocomplex molecular film is transferred onto the carrier. A single complex molecular layer film is produced in the above manner, but a single complex molecular layer cumulative film having a desired degree of accumulation is formed by repeating the above operations.

In order to transfer the single chain molecular layer onto the carrier, in addition to the above-mentioned vertical dipping method, methods such as the horizontal deposition method and the rotating cylinder method can be used. The horizontal adhesion method is a method in which the carrier is transferred by bringing it into horizontal contact with the water surface, and the rotating cylinder method is a method in which a cylindrical carrier is rotated on the water surface to transfer a single-chain molecular layer onto the surface of the carrier. In the vertical immersion method described above, when a carrier with a hydrophilic surface is lifted out of water in a direction transverse to the water surface, a monocomplex molecule layer is formed on the carrier with the host molecules of the host molecules facing toward the carrier.

When the carrier is moved up and down as described above, one single complex molecule layer is stacked on top of the other with each step. Since the direction of the film-forming molecules is reversed between the pulling process and the dipping process, this method forms a Y-shaped film between each layer in which the parent wood groups of the host molecules face each other, and the hydrophobic groups of the host molecules face each other. be done. On the other hand, the horizontal adhesion method is a method in which the carrier is brought into horizontal contact with the water surface and transferred, and a single-chain molecular layer with the hydrophobic group of the host molecule facing the carrier is formed on the carrier. in this way,
Even when accumulated, there is no change in the direction of the film-forming molecules, and an xy11 film is formed in which the hydrophobic group faces the carrier side in all layers.On the contrary, in all layers, the parent group faces the carrier side. The membrane is called a Y-type membrane.

The rotating cylinder method is a method in which a cylindrical carrier is rotated on the water surface to transfer a monomolecular layer onto the carrier surface.

The method of transferring the monomolecular layer onto the carrier is not limited to these methods, and when a large-area carrier is used, a method of extruding the carrier from a carrier roll into an aqueous phase may also be used.

Furthermore, the orientation of the aforementioned parent wood group and hydrophobic group toward the carrier is a general rule, and can be changed by surface treatment of the carrier.

In the above film-forming process, the in-plane orientation control of the film material has conventionally been achieved mainly by controlling the surface pressure. Except in the case of straight-chain fatty acids, it has been extremely difficult to obtain high orderliness. However, in the present invention, since an inclusion complex is used as a membrane material, a highly ordered membrane can be obtained relatively easily. That is, when the inclusion complex precipitates in a film form on the aqueous phase, there are bonds between host molecules and guest molecules, between host molecules and host molecules, and between guest molecules and guest molecules due to hydrogen bonds, van der Waalska, etc. The steric configuration between them is fixed, and each host molecule and guest molecule are arranged with crystal lattice order.

[B] A water-soluble guest molecule is dissolved in the aqueous phase. Next, host molecules are dissolved in a solvent and spread on the aqueous phase. At the same time, an inclusion complex is formed between the host molecule and the guest molecule, and the mixture is deposited in the form of a film. Regarding the combination of host molecules and guest molecules and the following film-forming operations, see [A
] According to the method shown in .

[C] Dissolving water-soluble guest molecules in the water phase Next, the host molecules and guest molecules of the intended inclusion complex are dissolved in a solvent, and this is spread on the water phase to form the inclusion complex. is deposited in the form of a film. The combination of host molecules and guest molecules and the following film-forming operations are based on the method shown in [A].

[D] Dissolve the host molecule in a solvent and develop it in the aqueous phase. Thereafter, using a closed system device, the gas phase side, that is, the space inside the device, is made into a guest molecule gas atmosphere. At this time, the guest molecules on the gas phase side are simultaneously included, and an inclusion complex is precipitated in the form of a film. This method is particularly effective when the guest molecule is a compound with a low boiling point and easily vaporized, such as acetone. The combination of host molecules and guest molecules and the following film forming operations follow the method shown in [A].

[E]! Using a closed system device, the gas phase side, that is, the space inside the device, is made into a guest molecule gas atmosphere.The host molecules and guest molecules of the zero-order inclusion complex are dissolved in a solvent, and this is poured onto the aqueous phase. to precipitate the inclusion complex in the form of a film. The combination of host molecules and guest molecules and the following film-forming operations were performed according to the method shown in [A].

The single chain molecular film and single chain molecular layer accumulation film formed on the carrier by the above method have high density and a high degree of order, and these films constitute the recording layer. By doing so, it is possible to obtain a recording medium having a high-density, high-resolution recording function capable of optical recording, thermal recording, electrical recording, or magnetic recording depending on the function of the inclusion complex.

When the produced single chain molecular film and single chain molecular layer cumulative film are used as a recording layer of a recording medium, recording is performed as shown below.

When host molecules are irradiated with light that can supply the energy necessary for polymerization, such as X-rays, gamma rays, and ultraviolet rays, polymerization occurs between the host molecules at the irradiated site as shown in formula m, forming polydiacetylene. Ru.

30≧m+n≧9. n≧0 Therefore, by exposing the entire surface of the single complex molecular film or the single chain molecular layer cumulative film, it is possible to dramatically increase the adhesive force with the substrate. In particular, chemical resistance (solvent resistance) is increased. t) When the guest molecule exhibits optical tri-membership due to full-surface exposure, the t± guest molecule also doubles, and when this is used as an optical recording medium, it becomes a dimer according to the Recording by irradiating light (ultraviolet light) with a wavelength equal to the absorption wavelength of the dimer to cause depolymerization, or because the host molecule is not depolymerized once it has been polymerized9, the entire surface is irradiated with light with a wavelength equal to the absorption wavelength of the dimer. After exposure to light and depolymerizing guest molecules, gamma rays,
Records can be made by irradiating with radiation, ultraviolet rays, etc. The recording method will be explained below.

1. When the guest molecule is a phototri-membered molecule, (1) A method using a wavelength equal to the absorption wavelength of the dimer of the guest molecule. When combined, an inclusion complex is formed in which the composition ratio (molar ratio) of host molecules to guest molecules is 1=2. When this single complex molecular film or single complex molecular cumulative film is irradiated with light that can supply the energy necessary for polymerization, such as gamma rays, It happens.

In these reactions, the distance between adjacent unsaturated bonds is 4A.
This can occur in the following cases, but in a single complex molecular film or a single chain molecular layer stacked film prepared by the method described above, not only can dimerization products be easily obtained, but also the duplex reaction can occur. Only one kind of the various isomer compounds or structures that are thought to be produced with the inclusion complex layer is produced, that is, the steric arrangement between the guest molecules in the inclusion complex layer is extremely orderly.

The dimer is based on a cyclobutane ring, wavelength 2? It has an absorption of Onm, but this wavelength 2? By irradiating with Qn+s ultraviolet light, the dimer returns to its original two monomer molecules. Therefore, when ultraviolet light with a wavelength of 270 nm is irradiated, depolymerization occurs only in that portion, and recording is made according to the pattern formed.

The recorded information is read, for example, by irradiation with visible light. In other words, as the conjugated system of the monomer is destroyed by polymerization, the absorption wavelength of visible light changes.The maximum absorption wavelength shifts to the lower wavelength side, so information can be reproduced by reading the change in the absorption spectrum. .

In addition to reading changes in absorption spectrum using visible light, regeneration can also be performed by reading changes in volume between monomer and three-membered pore diameter using the Schlieren method. This method is particularly suitable for a monomer molecular film or a monocomplex molecular layer stacked film of a compound having a structure in which the volume of the three-membered pore varies greatly compared to when it is a monomer. In addition, instead of depositing a single chain molecular film or a single chain molecular layer cumulative film directly on the substrate, Ss,
By forming a photoconductor layer such as Zn (1°CdS) and forming a single complex molecular film or a single chain molecular layer cumulative film on it, the difference in absorbance between the monomer and dimer can be electrically It is also possible to read the

■A method in which the entire surface is exposed to light at a wavelength equal to the absorption wavelength of the guest molecule dimer, and then recording is performed by doubling the guest molecule.

■The double guest molecule as shown in the formula is irradiated with the absorption wavelength of the cyclobutane ring (27(ln+i), depolymerized and returned to the monomer.) Next, according to a certain pattern, gamma rays,
Recording is performed by supplying the energy necessary for polymerization, such as X-rays and ultraviolet rays, to partially dimerize again.

In the optical recording medium mentioned above, the film thickness is particularly 100 to 30
00 A is preferred.

2. When guest molecules sublimate For example, when guest molecules such as No. 42-48 are combined, the composition ratio (101 ratio) of host molecules to guest molecules is l:
A 1 to 1:2 inclusion complex is formed. When these guest molecules are irradiated with laser light, electron beam, etc. having sufficient energy to dissociate from the inclusion complex and vaporize according to the pattern on this single-chain molecular layer or single-chain molecular layer accumulation film, the non-irradiated areas are exposed. In this case, since the guest molecule remains included in the host molecule, recording was performed according to the above pattern.

Reading of the recorded information is carried out using No.
42, this is done by reading the presence or absence of ultraviolet light absorption based on the carbonyl group of these compounds. Furthermore, structural changes in the film before and after irradiation with laser light or electron beam can be read by the Schlieren method, and this method is also effective when No. 42 to 4B are used as guest molecules.

In addition, by forming a single-chain molecular film or a single-complex molecular layer cumulative film containing No. It is also possible to read the difference electrically.

In the above recording medium, the film thickness is particularly 100 to 1000.
A is preferred.

As can be seen from their principles, these film-forming methods are very simple methods, and can provide recording media having the above-mentioned excellent recording function at low cost.

The carrier that forms the single-chain molecular film or the monolayer cumulative film in the present invention as described above is not particularly limited, but if a surfactant is attached to the surface of the carrier, the single-complex molecular layer will be transferred from the water surface. Sometimes, the single complex molecular film is disturbed and a good single chain molecular film or single chain molecular layer cumulative film cannot be formed, so it is necessary to use a carrier with a clean surface. Examples of carriers that can be used include glass, metals such as aluminum, plastics, ceramics, and the like.

A single-chain molecular film or a 1,000-layer cumulative film of a single complex on a carrier is sufficiently strongly fixed and hardly peels off or peels off from the carrier. An adhesive layer can also be provided between the molecular films or the monocomplex molecular layer stack. The adhesion force can also be strengthened by selecting the conditions for forming a monocomplex molecular layer, such as the hydrogen ion concentration of the aqueous phase, the ion species, the water temperature, the rate of raising and lowering the carrier/body, or the surface pressure.

Providing a protective film on a monomolecular film or a monomolecular layer stack is preferable in order to improve the chemical stability of the monomolecular film or monolayer stack; Depending on selection, the protective film may or may not be provided.

EXAMPLES The present invention will be explained in more detail by showing examples below.

Example 1 Optical recording medium using photodimerization reaction of guest molecules (3) V diacetylene diol as the host molecule and cinnamic acid as the guest molecule were dissolved in chloroform at a molar ratio of 1:2, and then dissolved at pH 8, 5. Cadmium chloride concentration 4
Ten layers were developed on a 4M aqueous phase. After the solvent chloroform was removed by evaporation, the surface pressure was increased to 35 dynes/cm to precipitate the inclusion complex in the form of a film. After this, while keeping the surface pressure constant, the glass substrate whose surface is sufficiently clean and hydrophilic is gently moved up and down in the direction across the water surface at a vertical speed of 7 cm/sin, and the single complex molecular film is deposited on the substrate. Transferred to a single complex molecular film and 3, 5, 9, 15.1
An optical recording medium having nine single-chain molecular layer cumulative films as a recording layer was manufactured. Using a zero-order high-pressure mercury lamp, the entire surface of these films was exposed to light to double the guest molecules (Formula ■). After polymerizing the host molecules (2), follow the pattern as shown in 1.
It was possible to record information on the order of 0 molecules by irradiating ultraviolet light with a wavelength of 270 nm to depolymerize guest molecules.

The recording was reproduced using a book that reads the absorption change in the wavelength range of 380 to 42 Onm accompanying the depolymerization of the duplicated guest molecules.

Furthermore, it was confirmed that the recording could be erased by exposing the entire surface of the upper recording medium to light using a high-pressure mercury lamp again. Note that this recording medium, which had been entirely exposed to light using a high-pressure mercury lamp, was fertilized in alcohol for about 30 seconds, and then information was recorded/reproduced using the above method, but no particular problems were found. That is, it was confirmed that the chemical strength of the recorded i-form was increased by polymerizing the host molecule.

Examples 2 to 8 Recording medium using sublimation of guest molecules (v) was used as the host molecule, and No. 4 was used as the guest molecule.
Using Samples No. 2 to No. 48, a single complex molecular film to a single complex molecular layer cumulative film having a thickness of 3° and 5.9 layers was prepared. A recording medium was produced by exposing the entire surface of such a single complex molecular film or a cumulative film of single complex molecular layers to light using a high pressure mercury lamp to polymerize host molecules.

When the created recording medium was irradiated with laser light according to a pattern using a carbon dioxide laser or an infrared laser,
Guest molecules were vaporized and removed only at the irradiated site, and information could be recorded on the order of 0 molecules. Recording and reproduction was possible by reading the presence or absence of guest molecules using the Schlieren method. No. 4 as a guest molecule
In the recording medium using 2, the absorption spectrum intensity of the part where the guest molecules are vaporized and removed (input 1161 = 28
0n) decreased, and recording and reproduction was possible even by measuring the absorption spectrum in the 2Bon layer.

These recording media are No., 42 to N'o', and 4, respectively.
When it was eroded into solution B, the guest molecules were included again in the site from which the guest molecules had been removed, erasing the recording and making it possible to rerecord.

According to this method, the adhesion force of the host molecule to the substrate is increased. Therefore, it has been found that the chemical strength of the recording medium becomes relatively high, and the number of times of repeated use can be increased to at least 100 times.

Patent applicant: Canon Co., Ltd.

Claims (1)

[Claims] Carries a monomolecular film or a monomolecular layer stack of an inclusion complex consisting of a polymerizable host molecule that has a hydrophilic site, a hydrophobic site, and an inclusion site in its molecule and a guest molecule that is included in the host molecule. A recording medium comprising a recording layer formed on top of the recording medium.